﻿/*******************************************************************************************
 * Copyright (c) 2006-2009 Alex Robson, Rob Simmons, Craig Israel, and Rachel Twyford
 *
 * Use of this software in any form requires that you have both 
 * read and agreed to the following terms:
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the "Software"), 
 * to deal in the Software without restriction, including without limitation 
 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions: 
 *
 * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, 
 * this list of conditions and the following disclaimer in the 
 * documentation and/or other materials provided with the distribution.
 * Neither the name of Nvigorate nor the names of its contributors may 
 * be used to endorse or promote products derived from this software without 
 * specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
 * DISCLAIMED. IN NO EVENT SHALL ANY CONTRIBUTOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ****************************************************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using Nvigorate.Common.Reflection;
using Nvigorate.Extensions;

namespace Nvigorate.Relational.State
{
    public static class ITrackStateExtenders
    {
        public static void MoveChildren<T>(this IEnumerable<T> children, Func<T, bool> selector, ITrackState newParent)
            where T : ITrackState
        {
            var adoptees = children.Where(selector);
            var childType = typeof (T);
            var parentType = newParent.GetType();
            var enumerableType = typeof (IEnumerable<T>);
            var targetProperty = Reflector.GetPropertyInfoList(parentType).First(
                p => p.PropertyType.Equals(childType) || Reflector.ImplementsInterface(p.PropertyType, enumerableType));

            if (targetProperty != null)
            {
                
                adoptees.ForEach(a => a.InstanceState.RelationshipChanged = true);
            }
        }

        public static void AdoptChild<T, P>(this T newParent, T oldParent, Expression<Func<T, P>> child)
            where T : ITrackState
            where P : ITrackState
        {
            var expr = ((child as LambdaExpression).Body as BinaryExpression).Left as MemberExpression;

            var property = expr.Member.Name;

            var orphan = child.Compile()(oldParent);
            Reflector.Write(oldParent, property, null);
            Reflector.Write(newParent, property, orphan);
            orphan.InstanceState.RelationshipChanged = true;
        }

        public static void AdoptChildren<T, P>(this T newParent, T oldParent, Expression<Func<T, IEnumerable<P>>> children)
            where T : ITrackState
            where P : ITrackState
        {
            var expr = ((children as LambdaExpression).Body as BinaryExpression).Left as MemberExpression;

            var property = expr.Member.Name;

            var orphans = children.Compile()(oldParent);

            IEnumerable<P> originalChildren = Reflector.Read(oldParent, property) as IEnumerable<P>;
            IEnumerable<P> parentChildren = Reflector.Read(newParent, property) as IEnumerable<P>;

            // if the predicate matches nothing, do nothing
            if(orphans == null)
            {
                return;
            }
            
            if(parentChildren == null)
            {
                parentChildren = orphans;
            }
            else
            {
                parentChildren = parentChildren.Concat(orphans);
            }

            originalChildren = originalChildren.Except(orphans);

            Reflector.Write(oldParent, property, originalChildren);
            Reflector.Write(newParent, property, parentChildren);
            orphans.ForEach(o => o.InstanceState.RelationshipChanged = true);
        }
    }
}